Vertical electrostatic copying machine with ghost free image projecting system

ABSTRACT

A vertical electrostatic copying machine includes a vertical illuminating chamber provided at its top with a horizontal original supporting window and at its bottom with a lens which focuses an image on a vertical plane by way of a mirror. The original is illuminated by a pair of curved reflector backed opposite lamps at the lower part of the chamber and planar specular reflectors depending from opposite edges of the window and so inclined as to reflect the light from the lamps in a manner to prevent ghost images. The copy paper is drawn from a source thereof forward of the upper part of the illuminating chamber and is advanced along a loop path downwardly, rearwardly and then upwardly to discharge, and along the path it is sequentially cut, charged, exposed, developed and dried. The copy paper source may be a roll or a stack of precut sheets.

c Unite States Patent 1 [111 3,732,004 Yamanoi et al. 1 May 8, 1973 54] VERTICAL ELECTROSTATIC 3,428,397 2/1969 Elmer ..355 70 x COPYING MACHINE WITH GHOST 3,282,177 1/ Stanton 3,498,715 3/1970 Gold FREE IMAGE PROJECTING SYSTEM 3,506,349 4/1970 Chen ..355/66 X [75] Inventors: Yorio Yamanoi; Masahiro Maeda,

both of T y Japan Primary ExaminerSamuel S. Matthews 731 Assignee: Minolta Camera Kabushiki Kaisha, j j a Hutchsm V osakajapan ttorneytan ey 0 er [22] Filed: Sept. 10, 1970 [57] ABSTRACT [21] Appl.No.: 70,976 A vertical electrostatic copying machine includes a vertical illuminating chamber provided at its top with horizontal ori inal su ortin window and at its bot- 3 F A l t P t D t a g PP g O] orelgn pp "on y a a torn with a lens which focuses an image on a vertical Sept. 11, 1969 Japan ..44/86371 plane by way of a mirror, The original is illuminated by a pair of curved reflector backed opposite lamps at [52] US. Cl ..355/3, 355/70 the lower part of the chamber and planar specular [51] Int. Cl. ..G03g 15/22 reflectors depending from opposite edges of the win- [58] Field Of Search ..355/3, 8, l4, 10, low and so inclined as to reflect the light from the 67 lamps in a manner to prevent ghost images. The copy paper is drawn from a source thereof forward of the [56] References C d upper part of the illuminating chamber and is advanced along a loop path downwardly, rearwardly and UNITED STATES PATENTS then upwardly to discharge, and along the path it is 2,602,370 7 1952 Dodin ..355 70 sequentially cut, charged, p developed and 3,592,544 7/1971 Brendel ...355/66 X dried. The copy paper source may be a roll or a stack 3,272,066 9/1966 Rice ...355/66X V ofprecut sheets. 3,567,344 3/1971 Masaya Ogawa et al. ...355/66 X 3,554,643 1/1971 Batter et a]. ..355/70 X 6 Claims, 5 Drawing Figures L 7 f 4i ,7 17 X ,7 6o i \k PATENTEU W 8 75 SHEET 1 OF 4 FIGJ mnsnmao 'nnggg PMENT UHAY 8 ma SHEET 2 [IF 4 mgmgg MAY 81973 SHEET 3 BF 4 FlG.3

INVENTOR. 70R '0 Yflmmvo/ and , nesmlmo mason VERTICAL ELECTROSTATIC COPYING MACHINE WITH GHOST FREE IMAGE PROJECTING SYSTEM The present invention relates generally to improvements in copying machines, and it relates more particularly to an improved compact vertical electrostatic copying machine.

The conventional electrostatic copying machine possesses numerous drawbacks and disadvantages. These machines generally employ a horizontally extending optical system in which the rays forming the image of the original extend along a long horizontal path with the consequence that the copying machine is very wide and occupies a very large area. This presents many difficulties in locating and mounting the machine, in effecting its relocation or replacement, and this is accompanied by many problems and inconveniences. Another drawback of the conventional electrostatic copying machine resides in the requirement that the position and number of light source elements for illumination be adjustable for copying different size originals, and in order to accommodate such adjustments a machine of large dimensions is necessitated.

It is therefore a principal object of the present invention to provide an improved copying machine.

Another object of the present invention is to provide an improved vertical electrostatic copying machine.

Still another object of the present invention is to provide an improved vertical compact electrostatic copying machine in which sharp reproductions are available and which is easy and convenient to operate and employ.

A further object of the present invention is to provide a compact electrostatic copying machine having an improved ghost free original illuminating and image projecting system.

In a sense the present invention contemplates the provision of an electrostatic copying machine including a casing in which a vertically extending illuminating chamber is disposed the top of the chamber having a window with a horizontal original supporting horizontal plate. A copy paper source is located in the casing upper part forward of the illuminating chamber and conveying means transports the copy paper along a looped path extending downwardly from the paper source, thence rearwardly below the illuminating chamber than upwardly to a discharge opening in the casing. Paper treating mechanisms are located along its path including in sequence a paper cutter where the paper source is a roll thereof, an electrical charger, an exposure station where the image of the original is projected on the paper, a developer and a drier. The image illuminating system includes at least one pair of light elements backed by curved reflectors directing the light onto the original and onto a pair of plane specular reflector plates which depend from opposite edges of the original support plate and are so inclined as to reflect light from the reflector backed light elements onto the original. The reflectors, light elements and original support plate are so related that all of the light from the reflector backed light elements which are not incident on the original support plate is reflected thereto by the planar reflector plates, and the projector lens is not exposed to any rays from the light elements either directly or as reflected from the planar reflectors or the original support plate to thereby prevent any ghost images.

The improved electrostatic copying machine is rugged, reliable, compact and convenient and produces sharp copies which are free of ghosts.

The above and other objects and advantages of the present invention may be appreciated by referring to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic vertical sectional view of a vertical electronic copying machine, according to the present invention;

FIG. 2 is a vertical sectional view of a paper feeder, usable in the machine of FIG. 1;

FIG. 3 is a schematic diagram of an optical system of the copying machine;

FIG. 4 is a schematic sectional view of illuminating means, usable in the copying machine of FIG.1; and

FIG. 5 is a sectional view, taken along the line V V of P164.

Like parts are designated by throughout the drawings.

Referring to FIG.1, a casing 1 of the copying machine holds an original-receiving glass plate 2 at the top thereof, and a lens system 3 is disposed below the central portion of the glass plate 2 by light-shielding walls 4, 5 secured to the casing. An illuminating chamber A is defined by the walls 4, 5 and the glass plate 2. A pair of light source elements 8, 9 with coacting reflective shades 6, 7 are disposed in the illuminating chamber A at suitable locations, so as to face the glass plate 2. An exposing means B is formed on the opposite side of the lens system 3, which exposing means is defined by light-shielding walls l0, 11, a mirror 12 carried by the walls 10, 11, and another light-shielding wall 13.

The front portion of the inside space of the casing 1 houses a photosensitive paper storing means 14, a paper cutter 16 disposed between a pair of paper feeding roller assemblies 15, an electric charger 17, and a conveyor belt 18 enclosing an exhaust fan 19 disposed at the back of the exposing means B for sucking air. The components in the front portion of the casing 1 are disposed in series, in the order as listed above. The bottom portion of the inside space within the casing 1 houses an automatic developer-feeder 20 and a developing means C, which comprises a plurality of rollers 22 facing an electrode 21 and an agitating belt 23. Photosensitive paper 24 is delivered from the developing portion C and passes through a drying means D at the rear portion of the casing l, and the paper is then collected at a photosensitive paper receiver 25. The drying means D includes a plurality of feeding rollers 26 and a blower fan 27, which blower sucks hot air from the light source elements 8, 9 throughpassages 30 bored through the light-shielding wall'5 for delivering it directly to the photosensitive paper 24 through passages 31 bored through another light-shielding wall 29.

As can be seen from the figure, the photosensitive paper 24 is stored in the form of a roll in the embodiment of FIG.1. FIG. 2 illustrates another embodiment of the photosensitive paper storing means suitable for precut sheets of photosensitive paper. In FIG.2, an inclined paper holder 32 is disposed within the casing 1 like numerals at a suitable front portion thereof. Each of the precut photosensitive paper sheets 34 is delivered to a curved guide passage 35 by a feeding roller 33, which is driven by a suitable driving means (not shown). The photosensitive paper sheet 34 from the guide passage 35 enters into an electric charger 17, and proceeds in the same manner as the preceding embodiment described hereinbefore referring to FlG.l. More particularly, the photosensitive paper sheet 34 moves vertically downwards after pausing momentarily at the exposing means B for static exposure. Thereafter it passes through a preagitated developing tank and is dried by utilizing heat emanating from the light source elements, and directed by the blower 2'7, and it is finally delivered out of the copying machine.

The details of the illuminating means A of FIG. 1 will now be described, by referring to FIG.3. The principles of FIG. 3 can also be used with a copying machine employing the paper storing means of FIG.2. An original 40 to be copied is placed on the original-receiving glass plate 2 so as to face downward. In the example of P163, a pair of reflectors 41, 42 are disposed adjacent the glass plate 2, for the purpose as will be described hereinafter.

In order to explain the function of the reflectors 41, 42, let it be assumed that the reflectors 41, 42 are not present in the FIG.3, and an imaginary light source element with a reflective shade 6 is present, as shown by dotted lines in the figure. A lens 3a functions to project an image of the original 40 on a photosensitive paper sheet. If the angle between a vertical to the original 40 on the glass plate 2 at one edge and stright line OY connecting the edge 0 and the nearest edge Y of the lens 3a is represented by 0 a line OZ can be drawn from the edge 0 with an angle 0= 9 relative to the aforesaid vertical in opposite direction to the line OY, as shown in the figure. If the imaginary light source element 8 is located outside of the line OZ relative to the original 40, there will be no ghost image of such imaginary light source element on the photosensitive paper by the lens 3a. Accordingly, if there is no reflector, the position of the imaginary light source element it should be adjusted, or the number of such light source elements must be controlled, depending on the size, or the position'of the edge 0, of each original 40, so as to prevent the formation of the ghost image. As a result, the overall dimension of the light source means becomes bulky.

According to the present invention, in order to obviate such difficulty, reflectors are disposed along opposite sides of the original with suitable angles thereto for preventing the formation of the ghost image. Such reflectors not only allow the light source elements to be located in the comparatively close proximity of the lens within the confinement of the reflectors, but also defines a dark box surrounding the light source elements for the efficient use of the light therefrom without wasting it.

Referring to FIG.3, all incident light beams to the lens 30, which are in a visual angle a defined by the aforesaid line OY connecting the left-hand edge of the original to the left-hand edge of the lens and another line OY' connecting the right-hand edge of the original to the right-hand edge of the lens, as seen in the figure, pass through the lens 3a. The mutual relation among the light source elements 8, 9, reflective shades 6, 7, (inclusive of the shape thereof), reflectors 41, 42, the original 40, and the lens 3a is such that undesirable reflected light beams are prevented from striking the lens 3a by the limitation defined by lines LP, LP connecting the light source element 9 to the lower edges 77a and 6a of the reflective shades 7 and 6, respectively. A line LP connecting the light source element 9 and the upper edge 7a of the reflective shade 7 coacts with the aforesaid line LP to define the illuminating domain at the left-hand-side of the original 40 by the light source element 9. It is apparent to those skilled in the art that similar limitation is applicable to the other light source element 8.

As a result, the light source elements 8 and 9 cooperate with the reflectors 41, 42 for uniformly illuminating the original 40. The angle between each of the reflectors 41 and 42 and the original 40 is such that the risk of the formation of ghost images of the light source elements 8 and 9 is completely eliminated while ensuring the aforesaid uniform illumination. The light source elements 8 and 9 are offset from the centers of radius 6 and 7' of the reflective shades 6 and 7, respectively, by a distance S towards the midpoint of the light sources, as shown in FIG.3. With such disposition of the light sources relative to the reflective mirrors, the reflected light beams through such centers of curvature are also convergent on the photosensitive paper for improving the optical efficiency of the light source means consisting of such light source elements.

H684 and 5 illustrate a practical example of illuminating means, according to the principles of FIG.3. In this example, scattering-preventive pieces or corner covers 43, 44 and 45, 46 are mounted on edges of the reflective shades 6 and 7, respectively, because the light beams scattered at the edges 6a, 6a and 7a, 7a may cause a ghost image on the photosensitive paper due to the non-directivity of such scattered beams. In order to prevent excessive brightness on the photosensitive paper around the central portion thereof due to the reflection of lens holder surfaces 47, 47, additional light-shielding walls 48, 48 are provided. Thus the light beams from the light source elements .8, 9 are prevented from reflecting at such lens holder surfaces. The additional light-shielding walls 48, 48 act to improve the lightproof properties of a dark box 49 enclosing the light source elements, reflective shades, and the reflectors. In the illustrated example, the dark box 49 is rectangular, and only two reflectors 41, 42 are disposed along comparatively longer vertical walls of the rectangular dark box, together with the coacting light source elements. The invention, however, is not restricted to such arrangement. For instance, additional two reflectors can be disposed along comparatively shorter walls of the rectangular dark box 49, so as to illuminate the original from four directions for achieving a still higher optical efficiency.

Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. An electrostatic copying machine comprising a casing having a front discharge opening and a top window, a horizontal transparent support plate registering with said top window, walls delineating an illuminating chamber communicating with and extending below said window, copy paper storing means located in said casing rearwardly of said chamber, means for advancing copy paper from said storing means along a predetermined path downwardly from said storage means to the lower path of said casi g and below the level of said chamber then forwardly and upwardly toward said discharge opening, electrical charging means, exposure means, developing means and drying means successively positioned along said predetermined path, and lens communicating wit said chamber along the central vertical axis of said window, characterized in that said illuminating chamber includes a pair of light emitting elements symmetrically disposed on opposite sides of the optical axis of said lens in said chamber, a curved first specular reflector disposed along the rear of each of said light elements, each of said light elements being offset from the center of curvature of the respective reflectors in a direction away from the rear concave face of said reflector, and a pair of specular reflector plates depending from opposite edges of said window at such angles to reflect light rays directly from and as reflected by said first reflectors to said window and substantially none of the light rays incident on said window plate directly from said light elements or as reflected by said specular reflectors being reflected by said window to said lens whereby to eliminate ghost images, said light emitting elements, first reflectors and reflector plates being arranged so that the light rays directly from each one of the light emitting elements illuminate a respective half of the window, and that the reflected regular light, consisting of the light rays from the light emitting element through the reflector plate to the window and the light from the light emitting elements through the first reflectors and the reflector plates to the window, illuminate all over the surface of the window.

2. The copying machine of claim 1 wherein the light rays emitted from the light emitting elements are delineated by upper edges of the first specular reflectors so that each light emitting element directly illuminates a respective opposite half of the window.

3. The copying machine of claim I wherein the reflected light rays, consisting of light reflected one or more times in the areas delineated by the lines from each light emitting element to the top edge of an opposite reflector and the opposite edge of said window respectively, and light reflected one or more times by the first specular reflectors, illuminate the full surface of the window.

4. The copying machine of claim 1, characterized in that the illuminating chamber comprises a rectangular dark box, and the light source elements and the first reflectors are disposed along comparatively longer vertical walls of the rectangular dark box, scatteringpreventive pieces being disposed along the edges of each first reflector.

5. The copying machine of claim 1 including nonreflecting light absorbing members extending along the edges of said first reflectors.

6. The copying machine of claim 1, wherein the illuminating means is surrounded by li ht-shielding walls defining a rectangular dark box, an the light sources and the coacting reflector shades are disposed along comparatively longer vertical walls of the rectangular dark box while disposing four reflectors therein for illuminating the glass plate from four directions. 

1. An electrostatic copying machine comprising a casing having a front discharge opening and a top window, a horizontal transparent support plate registering with said top window, walls delineating an illuminating chamber communicating with and extending below said window, copy paper storing means located in said casing rearwardly of said chamber, means for advancing copy paper from said storing means along a predetermined path downwardly from said storage means to the lower path of said casing and below the level of said chamber then forwardly and upwardly toward said discharge opening, electrical charging means, exposure means, developing means and drying means successively positioned along said predetermined path, and lens communicating wit said chamber along the central vertical axis of said window, charActerized in that said illuminating chamber includes a pair of light emitting elements symmetrically disposed on opposite sides of the optical axis of said lens in said chamber, a curved first specular reflector disposed along the rear of each of said light elements, each of said light elements being offset from the center of curvature of the respective reflectors in a direction away from the rear concave face of said reflector, and a pair of specular reflector plates depending from opposite edges of said window at such angles to reflect light rays directly from and as reflected by said first reflectors to said window and substantially none of the light rays incident on said window plate directly from said light elements or as reflected by said specular reflectors being reflected by said window to said lens whereby to eliminate ghost images, said light emitting elements, first reflectors and reflector plates being arranged so that the light rays directly from each one of the light emitting elements illuminate a respective half of the window, and that the reflected regular light, consisting of the light rays from the light emitting element through the reflector plate to the window and the light from the light emitting elements through the first reflectors and the reflector plates to the window, illuminate all over the surface of the window.
 2. The copying machine of claim 1 wherein the light rays emitted from the light emitting elements are delineated by upper edges of the first specular reflectors so that each light emitting element directly illuminates a respective opposite half of the window.
 3. The copying machine of claim 1 wherein the reflected light rays, consisting of light reflected one or more times in the areas delineated by the lines from each light emitting element to the top edge of an opposite reflector and the opposite edge of said window respectively, and light reflected one or more times by the first specular reflectors, illuminate the full surface of the window.
 4. The copying machine of claim 1, characterized in that the illuminating chamber comprises a rectangular dark box, and the light source elements and the first reflectors are disposed along comparatively longer vertical walls of the rectangular dark box, scattering-preventive pieces being disposed along the edges of each first reflector.
 5. The copying machine of claim 1 including nonreflecting light absorbing members extending along the edges of said first reflectors.
 6. The copying machine of claim 1, wherein the illuminating means is surrounded by light-shielding walls defining a rectangular dark box, and the light sources and the coacting reflector shades are disposed along comparatively longer vertical walls of the rectangular dark box while disposing four reflectors therein for illuminating the glass plate from four directions. 